Optical system of magnifying glasses



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OR 19.6@59030 i n I I L May l, 1928. l l 1,553,030 -ef L. E. w. VAN ALBADA Y OPTICAL srs'rsl 0F MAGNIPYING GLASSES Filed July 14, 1924 Foca? lengh 70mm "o v' lensI 1.535 so I' III4 um qu. III 1.617 56.5

Patented May l, 1928.

UNITED STATES PATENT OFFICE.

LIEUWE EVERT WILLEM VAN ALBADA, OF AMSTERDAM, NETHERLANDS, ASSIGNOB TO THE FIRM CARL ZEISS, OF JENA, GERMANY.

OPTICAL SYSTEM OF MAGNIFYING GLASSES.

Application led July 14, 1924, Serial No.

The subject of the present invention forms a. magnifying glass which, whilst being of simplified construction, only shows very slight image defects, particularly only an exceedingly slight distortion for a comparatively large field 0f vision. According to the present invention the optical system consists of a dispersive front member and a collective rear member which are somewhat apart, whereby the intermediate air-space is collective. If

R1 be the radius of curvature of the back surface of the front member,

R, the radius of curvature of the front surface of the rear member,

L the distance apart of the said two members. nl the refractive index of the glass of the lens having the radius of curvature R1, n2 the refractive index of the glass of the lens having the radius of curvature R2,

the said intermediate air-space has the refractive power 1 ni n2-1 (1"7l/1lm2-1) D R, l R2 L :R1-R, The condition that the said collective airspace is collective, reads therefore 1-n1 m-l (bimba-1) R1 R2 L R111. 0 Already in the event of each of the two members consisting of a single lens, the colour defects may be kept very slight, however, if particularly slight colour defects are to be attained, at least one of the two members is suitably composed of two lenses.

It has proved of special advantage to make the back surface of the rear member plane but it is still more advantageous to make the back surface of the front member plane too. If the back surface of the front member be plane, the radius of curvature is infinitely great (R1=). In that case the above condition that the intermediate air-space is collective, passes over into the condition.

726,028, and in Germany January 6, 1923.

Both members consist of the same glass as characterized by the values aD=1,523 v For the second example the following values, likewise for a focal length of 7 0 mm., hold good:

The following kinds of glass are used:

711D 'U Lens I 1,525 60 II 1,517 64 III 1,617 36,5

I claim 1. Optical system of a magnifying glass, consisting of a dispersive front member and a collective rear member which members are somewhat apart, between the radius of curvature R1 of the back surface of the front member, the radius of curvature R2 of the front surface of they rear member, the distance apart L of the said two members, and the refractive indices n, and n2 of the glass of the lenses having the radius of curvature is convex, lwhich members are somewhat 10A R1 and R2 respectively being the relation apart.

3. Optica-l system of a magnfyin Glass, 1 Rule-2R l-L(1 1) consisting of a dispersive front mem e?, the

back surface of which is plane, and a col- 2. Optical system of a magnifying glass, lective rear member, the front surface of 15 consisting of a dispersive front member`r the which is convex, while its back surface is back surface of which is plane, and a collecplane, which members are somewhat apart. tive real' member, the front surface of which L. E. WV. VAN ALBADA. 

